There are many avenues to seek child support from a noncustodial parent though there are also a few events which can limit those avenues. From what you have stated your avenues will be limited to the specific terms of your divorce decree. Your divorce decree SHOULD have listed an amount for child support and thus you would be looking at a scenario to enforce that order. If your decree did not list an amount then your options will be extreme;y limited. I suggest taking the divorce decree to an attorney who can read the specific text and give you an opinion as to what if anything can be done.
It really depends on your particular circumstance, but generally speaking - if there was a court document saying that he should pay you - then he could owe you the money he didn't pay. However, it really depends on the circumstance and there is not enough information to make an accurate assessment. Please see a lawyer about this.